To meet the demand for wireless data traffic having increased since deployment of 4G (4th-Generation) communication systems, efforts have been made to develop an improved 5G (5th-Generation) or pre-5G communication system. Therefore, the 5G or pre-5G communication system is also called a ‘Beyond 4G Network’ or a ‘Post LTE System’.
The 5G communication system is considered to be implemented in higher frequency (mmWave) bands, e.g., 60 GHz bands, so as to accomplish higher data rates. To decrease propagation loss of the radio waves and increase the transmission distance, the beamforming, massive multiple-input multiple-output (MIMO), Full Dimensional MIMO (FD-MIMO), array antenna, an analog beam forming, large scale antenna techniques are discussed in 5G communication systems.
In addition, in 5G communication systems, development for system network improvement is under way based on advanced small cells, cloud Radio Access Networks (RANs), ultra-dense networks, device-to-device (D2D) communication, wireless backhaul, moving network, cooperative communication, Coordinated Multi-Points (CoMP), reception-end interference cancellation and the like.
In the 5G system, Hybrid FSK and QAM Modulation (FQAM) and sliding window superposition coding (SWSC) as an advanced coding modulation (ACM), and filter bank multi carrier (FBMC), non-orthogonal multiple access (NOMA), and sparse code multiple access (SCMA) as an advanced access technology have been developed.
With the development of information and communication technologies, a variety of wireless communication technologies have been developed. Among them, WLAN is technology for allowing a user to wirelessly access the Internet in a particular service area such as home, company or aircraft, using a mobile terminal such as Personal Digital Assistant (PDA), laptop computer, Portable Multimedia Player (PMP), and the like, based on the radio frequency technology.
Owing to the increased utilization of WLAN, a mobile terminal user such as a laptop computer user may now work with increased mobility. For example, the user can take a laptop computer from his/her own desk to a conference room to attend a meeting while keeping the laptop computer connected to his/her local network to receive data and can access the Internet through a modem or a gateway in the local network without the constraints of the wired connection. Similarly, even business travelers can use the mobile terminal to access their own e-mail accounts in order to receive or send an e-mail or to check an e-mail.
The early WLAN technology was to support the rate of 1-2 Mbps with frequency hopping, spread spectrum and infrared communication by using a 2.4 GHz frequency in accordance with IEEE 802.11. Recently, with the development of wireless communication technologies, the WLAN technology makes it possible to support the rate of a maximum of 54 Mbps by applying Orthogonal Frequency Division Multiplexing (OFDM) technology and the like to WLAN. In addition, in IEEE 802.11, wireless communication technologies have been developed and put to practical use, for improvement of Quality of Service (QoS), AP protocol compatible, security enhancement, radio measurement or radio resource measurement, wireless access in vehicular environment, fast roaming, mesh network, inter-working with external network, wireless network management, and the like.
In the WLAN system, a UE performs an AP scanning process to find an accessible AP. The AP scanning process is a process in which a UE acquires a list of candidate APs that the UE will join in the succeeding joining process to be a member of a particular Extended Service Set (ESS), and also acquires information about each of the APs.
The AP scanning process includes a passive scanning method or an active scanning method. The passive scanning method is a method in which a UE receives a beacon frame that an AP transmits periodically (typically, every 100 ms), to check the presence of the AP. In this method, the UE requires time of 100 ms per channel depending on when the UE has acquired the beacon frame. The active scanning method is a method in which a UE directly sends a probe request frame to an AP, and upon receiving the probe request frame, the AP sends a probe response frame to the UE, thereby notifying the presence of the AP itself. The active scanning method is typically shorter than the passive scanning method in terms of the time that the UE scans an AP for each channel, but the UE should undesirably send an additional probe request frame. In addition, even the AP should undesirably generate an additional probe response frame in addition to the beacon frame.
Therefore, there is a need for an efficient AP scanning method for reducing the time required for AP scanning to allow a UE to quickly access an AP, and to reduce power consumption of a UE.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.